On Thu, 3 Jul 1997, Roland Franzius wrote:
> just define
> prd/: prd[a_,b_]+prd[a_,c]:=prd[a,b+c]
> Your example takes 1.9 s on my old 486dx2/66
> r.franzius
>
Hi Roland,
Thanks for the input on my question. Unfortunately, I think you might have
made a mistake. First, there is no difference between the statements
prd /: prd[a_,b_]+prd[a_,c_]:=prd[a,b+c]
and
prd[a_,b_]+prd[a_,c_]^:=prd[a,b+c]
Try out both statements and check ??prd. Secondly, I think you might have
missed the underscore after the c in the second prd. Without the
underscore, the collecting function won't work, and my example will not
work. As a test of your definition, make sure that
prd[x,y]+prd[x,z]
returns
prd[x,y+z]
Note that without the underscore, my example will run much faster, since
there is less generality in the prd definition.
Again, thanks for your suggestion.
Carl Woll